Atomization of strong sulfuric acid



March 11,1947. MTWLESTAD 2,417,386

ATOMIZATION OF STRONG SULFURIG ACID Filed Dc. ;7,. 194:5

.agio

M INVENTOR /v/r/W nnffmo,

ATTORNEY Patented Mar. 11, 1947 UNITED STATES PATENT OFFICE ATOMIZATION F STRONG SULFURIC ACID Nicolay Titlestad, White Plains, N. Y., assignor to Chemical Construction Corporation, New York, N. Y., a corporation of Maine Application December 17, 1943, Serial No. 514,636

3 Claims. 1

This invention relates to a process for the thermal decomposition of strong sulfuric acid such e description of a specic embodiment of the invention.

In my copending application Serial No. 446,719 led June 12, 1942, I have described a method for the thermal decomposition of strong sulfuric acid, including spent alkylation acid sludges, by injecting such acids into a furnace maintained at temperatures of i600-2400" F. The present invention represents an improvement over the injection methods which are described in that application, and is adapted particularly for use in large sulfurie acid plants wherein a decomposition furnace of great capacity is used. Although the invention in its broader aspects is not limited to large furnaces, it is a particular advantage of my present invention that it can be used to supply feeds of strong acids at rates as high as 3-5 tons per hour while still obtaining a complete and uniform atomization of the sludge.

I have found that a highly efficient and uni-l sludges having a high sulfuric acid content, such as spent alkylation acid containing about 80-90% sulfuric acid is obtained by a combination of mechanical dispersion and pneumatic injection. In the preferred embodiments of my invention the mechanical dispersion is obtained by the application of centrifugal force, while the pneumatic injection is obtained by the use of a compressed gas such as compressed air or steam. The application of centrifugal force to obtain a preliminary distribution of the acid or acid sludge en.. ables me to obtain very high injection rates, while the impingement of a compressed gas on the centrifugally produced spray results in the formation of a mist of extremely fine droplets which are readily decomposed in the furnace.

From the foregoing it will be seen that my invention in its broader aspects comprises the steps of first forming a spray of acid droplets by centrifugal action and then impinging a stream of compressed air or other compressed gas on this 2 initial spray to complete the atomization and inject the particles into the furnace. On the attached drawing I have illustrated one form of injector which is particularly well suited for applying the principles of my invention. drawing:

The single gure is a partial section, with other parts broken away, of a centrifugal atomizer having combined therewith a pneumatic injector for simultaneously applying centrifugal and pneumatic force to strong sulfuric acid.

Referring now to the drawing, reference numeral I designates generally a preferably cylindrical combustion furnace adapted for the thermal decomposition of strong sulfuric acid such as acid sludges at temperatures of i600-2400 F.

or higher. The conical inlet of said furnace is designated by reference numeral 2.k Mounted on a supporting plate 3 which is set over the orifice of said inlet is a gas ring 4 supplied with a feed pipe 5 and having burner jets for injecting a supplyV of hydrocarbon fuel into said furnace in amounts capable of maintaining the proper temperatures therein. Rods 1 are also attached to said supporting plate 3 and carry on their outer ends an annular supporting ring 8 which is adapted to hold in place the injectors employed in practicing the present invention. These injectors consist generally of an outer fixed pneumatic air or steam distributor 9 and an inner mechanical distributor l0 which is adjustably mounted on a supporting rod Il.

The pneumatic distributor 9 is made up of a spiral casing I5 having an outer wall it provided with a flange I i for engagement with the supporting ring 8 and an inner wall IS having a nished inner cylindrical surface I9 for sliding engagement with a corresponding element of the mechanical distributor Ill. The inwardly turned terminal portion of the inner wall is provided with a machined cylindrical inner surface 2t, and also carries a pivotally mounted check valve 2i which is adapted to close the orifice when the distributor i!) is in withdrawn position. The outer wall IS terminates in a nozzle 22 having an inwardly Y extending portion that terminates in a machined inner surface 23.

The essential element of the mechanical distributor li! is a power-driven rotary cup 25 mounted on a hollow shaft 26 supported in bearings 21 and 28 and forming part of the rotor of an electric motor Z. The cup has a cylindrical outer wall 30 but the inner wall 3| is tapered outwardly in order to facilitate the discharge of acid over the edge 32 thereof when the cup is rotated.

On this f The perforated inner end of a feed pipe 33 extends into the base of the cup 25, while the remainder of this pipe passes through the hollow shaft 26 and terminates in an elbow 311 which connects with a feed pipe 35 by way of a control valve 36. A perforated cylindrical shell 31 is mounted on the frame of the motor 29 concentrically of the'cup 25.and terminates in an inwardly turned flange 38 which ts closely around the outer cylindrical surface 3D of the cup. The entire assembly is adapted for close sliding engagement with the corresponding machined inner surfaces of the xed distributor 9 and nozzle 22 so that the frame of the motor will be supported by the machined surface I 9 and the cylindrical shell lwill form a gas-tight fit with the machined vsurfaces 2G and 23.

In operation the combined action of the mechanical and pneumatic distributors results in an extremely ne dispersion of the strong sulfuric acid oracid sludge while operating at highcapacities. The cup 25 is rotated rapidly while a stream of the acid is fed into the base thereof through the perforated pipe 33; 'The stream of acidiis converted into a radial spray as it passes over the rotating edge 32 of the cup, the droplets of acid'being flung outwardly by centrifugal force. Meanwhile, a stream of compressed air is fed stricted inner edge 3B thereof. Upon passage through this restricted orifice the compressed air is converted intoan annular blast which impinges on the radial spray of acid droplets and injects this spray into the furnace as `an 'extremely ne Although my invention in its broader aspects 'is not limitedby exact operating details, I have found as a further important feature thereof that optimum results are obtained when certain specific air pressures and ratios are adhered to. As has been noted above, a principal advantage of my present invention resides in the extremely high rate of feed that can be obtained when strong sulfuric acid and particularly sulfuric acid siudges such as'spent alkylation acid are atomized by combined mechanical and pneumatic action. A considerable amount -of energy is required to atomize such strong acids, and this is supplied by the compressed gas. In order to avoid the cooling effect of large volumes of cold air or other gas I have found that much better results are obtained when the necessarily cold compressed air is supplied in relatively small quantities but at high pressures. I prefer to use air at pressures of 10-25 pounds per square inch gage, and best results are obtained at pressures of about 16-22 pounds per square inch. With air or .other gas at this pressure it is possible to atomize as much as 3-'5 tons per hour of spent alkylation acid or other form of strong sulfuric acid with a rotating vthrough the pipe 40 into the spiral casing Iof the pneumatic distributor 9 and flows through orices in the cylindical shell 31 and past the recup of about 4-5 inches in diameter. Thus, for example, in a sulfuric acid plant utilizing 100 tons of spent alkylation acid per 24 hour day I have found that approximately 250 to 350 cubic feet per minute of air supplied at 16-20 pounds per square inch gage will produce an extremely fine and efficient atomization.

What I claim is:

1. In a process for the thermal Adecomposition of strong sulfuric acid by contacting it in a furnace with a flame obtained by the injectionof a fuel, the improvement which comprises providing said acid at the rate of 3-5 tons per hour, converting this acid into a radial spray, and injecting said spray into the furnace by impinging thereon an annular blast of air compressed to at least 16 pounds per square inch gage, said air being supplied at the rate of from about 250 to about 35i) cubic feet per minute.

2. A method of injecting strong sulfuric acid Yinto a furnace for the thermal decomposition 'thereof which vcomprises continuously feeding a stream of said acid at the rate of 3 5 tons per hour into ay zone in which a centrifugal force is exerted thereon and thereby breaking up andrdi'stributing said stream and discharging saidacid in'a radially expanding spray of acid droplets from said zone, and impinginguponsaid spray an annularstream of air compressed 4to atleast 16 pounds per square -inch gage at the' rateV of about 250 to about 350v cubic vfeet per minute,

said ,compressed air being injectedl substantially at a right angle to the radial-direct'ion-ofv said droplets, whereby said spray is furtheratomized and formed into an acid mist and injected'into the furnace 'by the propelling action of thecomf pressed air.

3. A method of 'injecting strong sulfuric nacid into a, furnace for the thermal vdecompositionv thereof which comprises continuously feeding a stream of said acid Vinto'a zone in whichaf centr-ifugal'force is exerted thereon, thereby breaking up and distributing said stream and discharging said acid inY a radially expanding spray 4of acid droplets from `said zone, and impinging uponH said spray an annular streamiof air compressed'to at least 16 pounds per square inch gauge, said compressed air'being injected substantiallyat an obtuse angle'to the radaldirection of said droplets, whereby said spray is further atomized and formed linto anV acid mist and injectedk into the furnace by the propellinglactionV of the 'compressed air.`

' NICOLAY TITLESTAD.

REFERENCES CITED f UNITED STATES PATENTSY Number Name 1 Date 1,976,528 Vandeveer Y'Oct. 9,1934 1,931,478 Barley .Oct.'24, 1933 1,672,054` l Holland June 5, -1928 2,097,271 ADebuch 4-- Oct. 26, 1937 2,261,995

Greenawalt Nov. 11, 1941 

